Published at the
Chat 'n Chew Cafe, June
2002URL:
http://www.kingcorn.org/news/articles.02/TMDS-0609.html

Some Corn Afflicted With TMDS Syndrome

few of the regular patrons of
the Main Street Café, at the corner of 1st and Walnut
streets, have begun to filter back for their morning coffee and rolls following
a couple of weeks of non-stop planting of corn and soybean. As the adrenaline
rush slowly fades away, some have been checking out the condition of the few
fields that were planted back in late April and early May as well as those that
have recently emerged from the late May planting frenzy.

Several individuals are reporting that some of the corn crop is now
suffering from a malady referred to as TMDS Syndrome, otherwise known as
Too Much Dang
Stress. Severe cases of TMDS merit the
substitution of stronger expletives for dang, but the net result is
the same: Corn that is unevenly stunted, putrid light green, yellow, white,
and/or striped with interveinal chlorosis; or extensive areas of fields with
severe stand loss.

The TMDS Syndrome is most pronounced on sandy knobs or knolls in fields
across the northern third of the state where most of the early-planted corn
exists this year. Other versions of TMDS occur elsewhere in the state in the
lower swales of fields or simply in areas of fields that are slightly lower
elevation than the surrounding areas.

The common causal link to all cases of TMDS is the occurrence of
multiple stresses and their timing with the developmental stage of the crop. As
with good comedy, timing is everything, especially when it comes to the effects
of severe early season stress on corn.

Two of my recent articles discussed the importance of
early root development in
corn and the consequence of stress occurring before
stand establishment is complete; i.e.,
before the nodal roots are well established (see links below). This has been
one of those years where multiple stresses have occurred in a time period in
which corn has, by and large, not yet been well established. Consequently, the
effects have been very dramatic in some fields.

The various stresses to choose from this year include the following.
Pick and choose from the list to customize your own list of yield limiting
factors thus far in 2002. Combine these stresses with hybrids with less than
excellent hybrid vigor, rates of starter fertilizer rates less than optimum, or
dangerously low soil pH and the results will be more severe.

Excessive rainfall leading to significant soil erosion that
washed away parts of fields and mudded over other parts of fields.

Four to five weeks of cool and wet soil conditions following
planting in late April that eventually resulted in significant outbreaks of
seedling
blight once the seed-applied fungicide gave up the ghost.

Four to five weeks of cool and wet soil conditions following
planting in late April that favored the development and activity of certain
corn nematodes on some of the sandier soils in northern Indiana.

The combination of four to five weeks of
cool and
wet soil conditions following planting in late April followed by a very
rapid transition to mid-summer type temperatures and strong drying winds.

Several frost and freeze events that resulted in stand loss
or above-ground leaf damage followed by one or more weeks of continued cooler
than optimum temperatures that stifled the recovery of the damaged crop.

Frequent and lengthy periods of cool, cloudy weather that
greatly reduced the rates of photosynthesis.

Sidewall and other soil compaction that restricted the
initial development of the seminal and nodal root system.

Cloddy
seedbeds that hindered both germination and early root development of the
corn crop.

What management steps can corn growers take in response to these
stresses? Unfortunately, most of the damage has already been done. A return to
decent corn growing weather (mid-80's and sunshine) will likely do wonders
towards improving the appearance of the crop, especially once the root system
develops more extensively and is better able to explore the soil environment
for nutrients.

With regards to the excessive leaching of nitrogen, magnesium, and other
nutrients, there are few certain options. The uncertainty lies with the
difficulty in knowing how far the nutrients have leached. If not deeply, then
the crop may still access them once its root system develops more extensively.
Consequently, "rescue" applications of nitrogen or magnesium fertilizers may
indeed cause a rapid greening of the crop, but may not result in increased
yields.

For other
information about corn, take a look at the Corn Growers Guidebook on the World
Wide Web at http://www.kingcorn.org

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